This invention pertains to liquid detergent compositions having improved machine compatibility, particularly in relation to enamel-coated surfaces. These compositions broadly comprise a synthetic organic surface-active agent, as an optional ingredient a detergent builder, and an additive level of a specific amino-silane with the further proviso that the claimed compositions have a pH, measured as is, in the range from 6 to 12.
The claimed technology can find beneficial application in all kind of liquid detergent compositions, such as highly concentrated builder-free detergent compositions but also in liquid detergent compositions containing conventional levels of surface-active agents and conventional builders. The essential amino-silane components act in the same way as silicates currently used in granular detergent compositions. Thus, the amino-silanes provide compatibility to the washing machine, however, with the important difference that they are capable of providing benefits over a broader range of pH conditions, they are very easily processable, and are effective at very low levels as compared to e.g. current silicates.
During the past decade, there has been a standing desire to develop liquid detergent compositions for use in lieu of conventionally formulated, mostly built, solid detergent compositions. This development trend purports to meet the consumers' desires for using lower washing temperatures, inclusive of cold water laundering. Granular detergent compositions have, as of yet, not been fully adapted to these laundry variations because of weaknesses in respect to dissolving speed, product insolubility, and cleaning efficiency.
The formulation flexibility for liquid detergent compositions is limited, particularly in respect to inorganic materials such as silicates. The latter compound is essential, in solid detergents, to ensure adequate compatibility of the washing machine to the laundry liquor, in particular of enamel-coated surfaces. As of yet, no suitable silicate-substitutes for convenient use in liquid detergent composition have been developed. Thus, there was a standing need to make available suitable silicate-substitutes. A satisfactory substitute shall exhibit its functionality not solely at relatively high alkaline pH such as needed by silicates, but over a broad range of conditions extending from e.g. neutral to alkaline (pH 6-12) conditions as can be found in liquid detergents. The silicate-substitute shall furthermore be compatible to the physical state of the matrix and to the individual components, for example, it must allow the preparation of homogeneous compositions and not be subject to deactivation/precipitation phenomena.
Silanes and amino-silanes are widely used in the chemical industry, mostly as coupling agents between inorganic and organic surfaces. These compounds have also found application for metal-surface protection. The protective treatment is applied from an aqueous medium, possibly from solvent systems containing lower alcohols and water, depending upon the characteristics of the silanes. Representative of this state of the art are: U.S. Pat. No. 3,085,908, Morehouse et al., U.S. Pat. No. 3,175,921, Hedlund, and French Pat. No. 1.207.724, Morehouse et al.
The preparation of a broad class of gamma-amino-propylalkoxysilanes is known from German Application DOS No. 17 93 280.
Silanes, inclusive of amino-silanes, have been used in industrial fiber treatment technology, mostly in combination with polysiloxanes. This art is represented by German Patent Applications DOS Nos. 27 26 108; 14 69 324; DAS No. 23 35 751; and U.S. Pat. No. 4,152,273, Weiland.
Quaternized amino-silanes are known, from U.S. Pat. No. 4,005,118, Heckert et al. and U.S. Pat. No. 4,005,025, Kinstedt, to be suitable for conferring soil release properties to metallic and vitreous surfaces upon application from a wash or rinse-solution. The like quaternized amino-silanes, upon incorporation in aqueous detergents, are subject to deactivation, possibly following polymerization during storage.
It is also generally known that silane metal-surface treatment is usually carried out under slightly acidic conditions (pH 3-5) in order to prevent polymerization of the silane monomers in the aqueous medium which polymerization is known to decrease the effectiveness of the surface treatment.
It is an object of this invention to formulate liquid detergent compositions having machine compatibility comparable to silicate containing granular detergent compositions.
It is a further object of this invention to formulate homogeneous and storage stable liquid detergent compositions, i.e., compositions which are not subject to phase separation and deactivation upon storage.
Yet another object of this invention is to formulate liquid detergent compositions containing a machine compatibilizing agent which is, at least, as effective as conventional silicates while being used at lower levels.